Bi-directional Overrunning Clutch Split Roll Cage Design
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Solution Overview
Problem
Current bi-directional overrunning clutches for primary drive axles are complex and unreliable, particularly in applications like snowblowers and all-terrain vehicles, as they can lead to reverse engagement issues when one hub overruns, causing the vehicle to behave like a solid axle.
Innovation Solution
A bi-directional overrunning clutch design featuring a split roll cage configuration with an intermittent coupler and friction disk mechanisms, where the coupler's radially extending teeth allow one roll cage to index relative to the other, preventing reverse engagement by creating a gap that only permits forward or rear cam surface contact, ensuring proper torque distribution and preventing reverse cam surface interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single roll cage configuration is used, then the structure is simpler, but reverse engagement occurs causing the vehicle to behave like a solid axle when one hub overruns
Solution Approach 1:
The single roll cage is divided into two separate roll cages (first roll cage and second roll cage), each associated with a respective hub. This segmentation allows independent control of each hub's engagement, preventing reverse engagement while maintaining structural simplicity through modular design.
Solution Approach 2:
A coupler is introduced as an intermediary component between the two roll cages. The coupler selectively couples the roll cages to each other, enabling controlled interaction that prevents reverse engagement while allowing normal operation. This intermediary mechanism resolves the contradiction by adding minimal complexity to achieve the reliability goal.
2Manufacturing precision
If friction disk mechanisms are added to index roll cages, then manufacturing tolerances can be larger, but the device complexity increases
Solution Approach 1:
Friction disk mechanisms are incorporated into each hub assembly, utilizing friction as a controllable parameter to index the roll cages. This allows the system to accommodate larger manufacturing tolerances by using friction-based adjustment rather than precision mechanical indexing, thereby improving manufacturability while adding only moderate complexity through the inclusion of friction disks and springs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances reliability and simplicity by preventing reverse engagement, maintaining positive driving engagement while allowing overrunning, and accommodating larger manufacturing tolerances, thus improving the clutch's performance and durability in wheeled machines.
Implementation Method 1
The spring is compressed between the end cap and the roll cage for biasing the friction member into frictional contact with the contact surface of the hub
Implementation Method 2
The rollers surrounding each hub are spaced about an associated hub and adapted to wedgingly engage between the hub and the inner cam surface when one of the hub and the housing is rotated with respect to the other of the hubs
Data Source
AI summary
A bi-directional overrunning clutch includes a housing and a pair of hubs substantially coaxially aligned within the housing. A pair of roll cages position a plurality of rollers between each hub and an inner cam surface of the housing. The rollers are positioned to wedge between the hub and the inner cam surface when one of the hub and the housing is rotated with respect to the other. End caps are attached to the housing adjacent to the hubs. A friction disk mechanism includes a friction plate rotating in combination with each the roll cage and a spring compressed between the end cap and the roll cage for biasing the friction member into frictional contact with the hub. An intermittent coupler is located between each roll cage and configured to engage the roll cages so as to permit indexing of one roll cage relative to the other.